In recent years, an electrode pad made of an Al—Cu alloy having a resistance lower than that of an Al—Si—Cu alloy and having a high electromigration resistance has been used.
For example, Japanese Patent Application Laid-Open Publication No. 2009-177104 (Patent Document 1) discloses a technique of improving reliability of a bonding region between an Al—Cu pad and a CuP wire in a high-temperature operation by providing a plurality of alloy layers whose Al—Cu composition ratios are different from each other to the bonding region between the Al—Cu pad and the CuP wire.
Also, Japanese Patent Application Laid-Open Publication No. 2010-205974 (Patent Document 2) discloses a technique of suppressing formation of a non-bonding part in a Cu wire by covering the uppermost surface of an electrode with an Al—Cu compound layer.